Proper VSync

[robertpfeiffer]

• with vsync=1 and SCALED, pg.display.update already blocking on my machine
• allow querying of screen refresh rate, via SDL_GetCurrentDisplayMode maybe as pg.display.get_refresh_rate() -> int
• warn if clock.tick is slower than screen refresh rate
• add GPU render path without scaling
• force GPU render path when vsync is requested without additional parameters
• use presentvsync when vsync is enabled
• should that include the SDL_HINT_RENDER_VSYNC hint? If yes, query that and force GPU render path too
• either deprecate list_modes and mode_ok or make them refresh rate and vsync aware
  • deprecate list_modes
  • add list_fullscreen_modes with vsync support
• investigate adaptive vsync with renderer (result: it's not a thing!)
• add environment variable to disable fullscreen_desktop and force HW fullscreen like it's 1999 (for @fladd and expyriment)
• interactive test program for vsync
• test on KMSDRM
• test on Mac
• test on wayland

[robertpfeiffer]

Should toggle_fullscreen() change the display surface resolution? Should toggle_fullscreen change the display surface resolution with resizeable?

[robertpfeiffer]

I checked with MangoHUD. It works perfectly and as expected on XFCE+X11. No jitter, no tearing.

[robertpfeiffer]

Same on wayland. Just works.

[robertpfeiffer]

KMS/DRM also works. This is the only platform where vsync actually makes a difference for tearing. On Sway and X11, it doesn't tear, but it just renders extra frames at 90 FPS. On KMSDRM, it tears in two places at once at 90 FPS, and in one place at 30 FPS. My screen is set to 60 FPS.

[robertpfeiffer]

Adaptive vsync is not possible with Renderer

[robertpfeiffer]

@MyreMylar @Mega-JC Any thoughts on these?

• allow querying of screen refresh rate
• warn if clock.tick is slower than screen refresh rate